From U.S. Pat. No. 3,888,956 a method is known for production of granules from a melt, especially from molten iron, in which a stream of molten iron is caused to fall against a horizontal, fixed member whereby the melt, due to its own kinetic energy, is crushed against the member and formed into irregularly sized droplets which move upwards and outwards from the member and fall down into a liquid bath of cooling medium situated below the member. While it is possible to produce metal granules using this known method, the method has a number of drawbacks and disadvantages. In particular, it is not possible to control the particle size and particle size distribution to any significant extent since the droplets which are formed when the molten metal hits the member will vary from very small droplets to rather large droplets. With production of granules from ferroalloy melts such as, for example, FeCr, FeSi and SiMn, a substantial amount of granules with a particle size below 5 mm are produced. In the production of ferrosilicon granules the amount of particles having a particle size below 5 mm is typically in the range of 22 to 35% by weight of the melt granulated and the mean particle size is about 7 mm. Ferrosilicon particles having a size below 5 mm are undesirable, and particles having a particle size below 1 mm are especially undesirable as such particles will be suspended in the liquid cooling medium and thereby necessitate continuous cleaning of the cooling medium.
From Swedish Patent No. 439783 it is known to granulate, for example, FeCr by allowing a stream of molten FeCr to fall down into a water-containing bath wherein the stream is split into granules by means of a concentrated water jet arranged immediately below the surface of the water bath. This method yields a rather high amount of small particles. In addition, the risk of explosion is increased due to the possibility of trapping water inside the molten metal droplets Due to the very turbulent conditions created by this method of granulation, the number of collisions between the formed granules will be high, which also increases the risk of explosion.